Refrigeration system including liquified gas tank



Oct. 22, 1968 J. F. WATKINS 3,406,533

REFRIGERATION SYSTEM INCLUDING LIQUIFIED GAS TANK Filed Feb. 13, 1967 2 Sheets-Sheet 1 United States 3,406,533 REFRIGERATION SYSTEM INCLUDING LIQUIFIED GAS TANK James F. Watkins, Chicago, 111., assignor to Cryo-Cool Corporation, Chicago, 111., a corporation of Illinois Filed Feb. 13, 1967, Ser. No. 615,819 Claims. (Cl. 62-217) ABSTRACT OF THE DISCLOSURE This invention relates to improvements in a refrigeration system and more particularly to improvements in a system for refrigerating or air conditioning any volume or space by vaporizing a liquid gas at a controlled rate.

A primary object of this invention is a refrigeration system wherein a liquid gas is converted to the vapor state at a controlled rate through use of an efficient and simplified system that is economical to operate.

A further object is a versatile refrigeration system that is adaptable to a variety of uses including an improved means for ventilating the air so that the refrigerated air may circulate.

Another object is a system that provides a dual means of refrigerating a space or volume while still providing an effective control over the refrigerant in both the liquid and vapor state.

Another object is an improved refrigeration system which utilizes a refrigerant that has a large gas to liquid expansion ratio thereby eliminating a large and bulky cold reservoir.

Another object is a refrigeration system which has an effective temperature control over the space to be refrigerated even though it utilizes a refrigerant with an extremely low temperature in the liquid state.

Other objects will appear from time to time in the ensuingspecification and drawing in which:

FIGURE 1 is a diagrammatic view of the refrigeration system;

FIGURE 2 is a diagrammatic view of another form of this invention, and

FIGURE 3 is a diagrammatic view of still another embodiment of the refrigeration system.

This refrigeration system 10 utilizes a reservoir of liquid gas and a network of conduits and thermo-tube coils and/or cold plates through which a liquid gas is passed and vaporized at a controlled rate. The thermotube coils and/or cold plates act as an evaporator 12 wherein the liquid gas is convert-ed to vapor by atomization and absorption of heat from the space to be cooled.

The necessary refrigeration may be supplied by one or both of two alternative methods. One method consists of a means to draw air across the evaporator 12 thereby forcing cold air to circuate in the space to be refrigerated. The other method consists of releasing the vapor derived from the liquid gas at a controlled rate within the space to be refrigerated. Both methods may be used at the same time or each method may be used alternatively, depending on the conditions in the space to be refrigerated.

The system is adaptable to a variety of uses and may be atent O used to refrigerate or air condition any volume or space. This system will provide the necessary degree of control both as to temperature of the volume or space to be refrigerated and as to use of the liquid refrigerant itself.

The refrigeration system 10, as shown in FIGURE 1, comprises a tank or container 14 which acts as a cold reservoir for a quantity of liquid gas. The tank or container 14 may be any suitable vacuum type and may be made from any suitable material such as metal. The cold reservoir stores the liquid gas until needed and is in communication with a conduit or fill pipe 16 which may be operated by a hand valve or any other type of valve mechanism. Another conduit with a safety pop off valve, which is not shown, may be used as a tank exhaust means to relieve the tank or container 14 from excessive pressures.

As shown in FIGURE 1 a gas distributor 18 may be connected to the fill pipe 16 leading from the cold reservoir. The gas distributor 18 reduces and divides the refrigerant into six independent fill conduits 20, 22, 24, 26, 28 and 30 which each lead to a thermo-tube coil 32, 34, 36, 38, 40 and 42. In addition the gas distributor 18 divides the system into two substantially identical networks with three of the fill conduits 20, 22 and 24 leading in one direction while the three remaining conduits 26, 28 and 30 lead in the opposite direction.

The thermo-tube coils 32, 34, 36, 38, 40 and 42 in this embodiment are of different sizes preferably with four of the coils 32, 34, 38 and 40 having larger diameter loops than the two remaining coils 36 and 42. In each network two of the larger coils encircle one of the smaller coils, as shown in FIGURE 1.

The thermo-tube coils 32, 34, 36, 38, 40 and 42 play an important role in the operation of this system. In these coils the liquid gas is converted to a vapor by a process of atomization combined with the absorption of heat from the space to be cooled. The gas distributor 18 reduces the liquid gas to a finer spray than when it entered the system from the cold reservoir thereby facilitating vaporization of the liquid gas. This feature combined with the fact that the thermo-tube coils 32, 34, 36, 38, 40 and 42 are at a higher temperature then the liquid gas when it enters the coils causes the refrigerant to vaporize in the evaporator. In addition, the size, shape, and placement of the coils also helps produce optimum conditions during vaporization.

From the thermo-tube coils 32, 34, 36, 38, 40 and 42 the substantially vaporized refrigerant is passed through six connecting thermo-tube exhaust conduits 44, 46, 48, 50, 52 and 54 with three conduits each corresponding to their respective network of coils. Each exhaust conduit is preferably approximately the same size with each network of conduits leading to a gas exhaust distributor 56 and 58.

Conduits 60 and 62 lead from each gas exhaust distributor 56 and 58 to a manifold conduit 64. This manifold conduit 64 then connects to a first solenoid valve 66.

The solenoid valve 66 is preferably thermostatically operated, as shown in FIGURE 1. The thermostat 68 and thermostat bulb 70 monitor the temperature of the cooling coils 32, 34, 36, 38, 40 and 42 wherein the temperature of these coils is proportional to the temperature of the space to be refrigerated. The thermostat 68 may be set at any desired temperature, however, for refrigeration purposes it is normally set at -40 F.

The thermostat 68 may be connected to a voltage source 72 through electrical connections or leads 74 and 76 and is shown in FIGURE 1 with the electrical positive lead 74 connecting the thermostat 68 to the power source 72 and the electrical negative lead 76 connecting the solenoid valve 66 to the thermostat 68.

A conduit 78 connects the first solenoid valve 66 to a second solenoid valve 80. The second solenoid valve 80 may be operated by a manual single pole switch 82 and is connected to the power source 72 by an electrical positive lead 84 and an electrical negative lead 86. These two solenoid valves 66 and 80 provide an effective temperature control for the volume or space to be refrigerated.

From the second solenoid valve 80 the refrigerant may be exhausted or discharged through one of two conduits. One conduit is an outside exhaust conduit 88 and leads to the atmosphere. The other discharge conduit 90 has a muffler 92 and may be used to discharge the vaporized liquid to the space being refrigerated.

As with any refrigeration or air conditioning system it is necessary to have a means for ventilating the air so that the refrigerated air may circulate. A pair of ventilating fans 94 and 96 and motor 98 are preferably provided for this purpose, as shown in FIGURE 1. These ventilating fans 94 and 96 and motor 98 are used to draw air across the cooling coils 32, 34, 36, 38, and 42 for circulating the cold air within the space to be refrigerated.

As shown in FIGURE 1 each network of thermo-tube coils is attached to a blower fan with an electrical positive lead 100 connected to the power source 72 and an electrical negative lead 102 connected to the first solenoid valve 66.

When the vapor is discharged into the space to be refrigerated it may then be circulated by the blower fans 94 and 96. This provides a suitable circulation means for forcing a flow of air across the coils which are cooled by the liquid gas vapor. As the temperature in the air of the space to be refrigerated drops and the temperature of the cooling coils 32, 34, 36, 38, 4t) and 42 drops in accordance therewith the thermostat 68 will open at a predetermined temperature to close the solenoid valves 66 and 80. This is the temperature at which sufficient cooling is provided so that additional temperature drop is not desired. However, it is often important to maintain circulation of the air within the space to be cooled, and thus the blower fans 94 and 96 may continue to run even though the system has temporarily stopped discharging the vapor to the space to be refrigerated.

FIGURE 2 shows another embodiment of this invention. In this embodiment a tank or container 110 acts as the cold reservoir and is connected to an evaporator 112 by a conduit or fill pipe 114. The evaporator 112 consists of a first cold plate 116 connected in series with a first thermo-tube coil 118 which in turn is connected in series with a second cold plate 120.

The second cold plate 120 is connected in series with two thermo-tube coils 122 and 124 which are connected with a third cold plate 126. The third cold plate 126 then leads to two thermo-tube coils 128 and 130 which lead out of the evaporator through a conduit 132. A dual blower fan 134 and motor 135 are also provided to circulate the refrigerated air across the evaporator 112.

As in the embodiment shown in FIGURE 1, two solenoid valves 136 and 138 are provided to regulate the temperature of the space to be refrigerated. The first solenoid valve 136 is preferably regulated by a thermostat 140 and thermostat bulb 142. The thermostat 140 may be connected to a voltage or power source 144 by electrical connections or leads 146 and 148 much in the same manner as described for the first embodiment. The second solenoid valve 138 may be operated by a manual single pole switch 150 and is preferably connected to the power source 144 through electrical connections or leads 152 and 154.

As in the embodiment shown in FIGURE 1 the vaporized liquid may be either discharged through a muffler 156 which leads to the space to be refrigerated or, if desired, to the atmosphere through a conduit 158.

FIGURE 3 shows another form of my invention which is substantially similar to the embodiment shown in FIG- URE 2. In the embodiment shown in FIGURE 3 the thermo-tube coils of FIGURE 2 have been removed from the system and the evaporator 112 consists of a series of three cold plates 116, 120' and 126. The rest of the system is substantially identical with the system shown in FIGURE 2.

The use, operation, and function of this invention are as follows:

As previously mentioned a tank or container 14 or acts as a cold reservoir for a quantity of liquid gas which may be either pumped or released into the refrigeration system through a fill pipe 16 or 114. The liquid gas may then pass through either a gas distributor 13 and a system of conduits to an evaporator 12, as shown in FIGURE 1, or through a. fill pipe 114 directly to the evaporator 112, as shown in FIGURES 2 and 3. The evaporator 12 or 112 may consist of a dual network of thermo-tube coils 32, 34, 36, 38, 40 and 42, as shown in FIGURE 1; or it may consist of a series of cold plates 116, 120, and 126 and thermo-tube coils 118, 122, 124, 128 and 130, as shown in FIGURE 2; or it may simply consist of a series of cold plates 116', and 126', as shown in FIGURE 3. It is important to note that in the evaporator 12 or 112 the liquid gas expands until it is substantially vaporized.

From the evaporator 12 or 112 the liquid gas is passed through a system of conduits to the solenoid valves 66 and St) or 136 and 138. Since the vapor flow through the evaporator must be stopped from time to time to maintain an exact temperature control, means must be provided to perform this function. These means are the solenoid valves 66 and 30 or 136 and 138. The solenoid valves 66 and St) or 136 and 138 prevent excessive amounts of liquid gas from being used and wasted, in addition to providing a complete temperature control and regulation. The first solenoid valve 66 and 136 is preferably operated by setting a thermostat 68 or at the desired temperature. If the refrigerant is at the desired temperature it will continue to flow from the first solenoid valve 66 or 136 to a second solenoid valve 80 or 138 which is preferably operated by a manual single pole switch 82 or 150.

From the second solenoid valve 80 or 138 the gas may be exhausted or discharged through either the outside exhaust conduit 88 or 158 to the atmosphere or, if desired, through a muffler 92 or 156 into the space being refrigerated. This is done so that the temperature will drop much faster in the space being refrigerated. This will also lower the oxygen content of the air to prevent spoiling of produce such as vegetables and fruit.

In addition a means to circulate the refrigerated air across the coils and/or cold plates and into the space to be refrigerated is preferably provided. This means is shown in FIGURE 1 as blower fans 94 and 96 with motor 98 and in FIGURES 2 and 3 as dual fan 134 and motor 135.

It has been found that liquid nitrogen is one of the best liquid gases to be used as a refrigerant or cooling agent because of its commercial availability at a low cost and its large gas to liquid expansion ratio. In addition it has the advantage of an extremely low temperature of approximately -320 F. in the liquid state.

If liquid nitrogen is used in this system the temperature of the nitrogen as it enters the evaporator 12 or 112 is approximately 320 F., however, as it passes from the evaporator to the solenoid valves 66 and 80 or 136 and 138 the temperature rises to approximately 72 F. As previously mentioned the thermostat which regulates the temperature at the first solenoid valve 66 or 136 is normally set at --40 F. for refrigeration. The volume or space being refrigerated is, of course, at a higher temperature than -40 F.

It is also important to note that the system just described is capable of continuous operation for a considerable length of time before it is necessary to replace the liquid gas supply.

It is understood that this invention is not confined to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms as may come within a scope of the following claims.

I claim:

1. A refrigeration system for cooling or air conditioning any volume or space by vaporizing a liquid gas at a controlled rate, comprising:

(a) a source of liquid gas,

(b) an evaporator wherein said liquid gas is passed and substantially vaporized,

(c) a means for regulating the flow of vaporized gas to provide a complete temperature control of the space to be refrigerated,

(d) a discharge conduit having a mufiier to discharge the vaporized liquid as desired to the space being refrigerated,

(e) a system of conduits for connecting said source of liquid gas with said evaporator and said means for regulating the how of vaporized gas to said discharge conduit, and

(f) a means for ventilating the air across said evaporator so that the refrigerated air may circulate.

2. The structure of claim 1 wherein said source of liquid gas is contained in a tank until needed and further the supply of said liquid gas may be regulated by a valve mechanism controlling the amount of liquid gas that enters the system.

3. The structure of claim 1 wherein a gas distributor is included in the system between said source of liquid gas and said evaporator for reducing the liquid gas to a finer spray than when it entered the system.

4. The structure of claim 1 wherein said evaporator consists of a plurality 'of thermo-tube coils at a higher temperature than the liquid gas when it entered the coils thereby absorbing heat from the space to be cooled and substantially vaporizing said liquid gas.

5. The structure of claim 1 in which said evaporator consists of a plurality of thermo-tube coils wherein some of said coils have loops of larger diameter than the remaining coils and further said coils are so arranged that the larger diameter coils encircle the smaller diameter coils.

6. The structure of claim 1 wherein said evaporator consists of a plurality of cold plates and thermo-tube coils connected in series.

7. The structure of claim 1 wherein said evaporator consists of a plurality of cold plates connected in series.

8. The structure of claim 1 wherein said means for regulating the flow of vaporized gas includes a first solenoid valve and a second solenoid valve and further said first solenoid valve is thermostatically operated and said second solenoid valve is operated by a manual single pole switch to monitor the temperature of said evaporator and provide an effective temperature control for the space to be refrigerated.

9. The structure of claim 1 further characterized by an outside exhaust conduit to discharge said vaporized gas to the atmosphere as desired.

10. The structure of claim 1 wherein said means for ventilating the air across said evaporator includes a pair of ventilating fans and a motor for circulating the cold air within the space to be refrigerated.

References Cited UNITED STATES PATENTS 2,475,755 7/ 1949 Pearson 62 -5l4 2,496,816 2/ 1950 Schlumbohm 62--5 14 3,092,977 6/1963 Skinner 62-514 MEYER PERLIN, Primary Exal'm'ller, 

